A multilayer photonic structure is described that strongly reflects incident sunlight while emitting heat selectively through an atmospheric transparency window to outer space; this leads to passive cooling under direct sunlight of 5 degrees Celsius below ambient air temperature, which has potential applications in air-conditioning and energy efficiency.

/pdf/passive-radiative-cooling-below-ambient-air-temperature-4ldemmkn87.pdf

Passive radiative cooling below ambient air temperature under direct sunlight

Transparent conductors as solar energy materials: A panoramic review

Forest management, coarse woody debris and saproxylic organisms: Fennoscandian boreal forests as an example

Atmospheric water is a resource equivalent to ~10% of all fresh water in lakes on Earth. However, an efficient process for capturing and delivering water from air, especially at low humidity levels (down to 20%), has not been developed. We report the design and demonstration of a device based on a porous metal-organic framework {MOF-801, [Zr6O4(OH)4(fumarate)6]} that captures water from the atmosphere at ambient conditions by using low-grade heat from natural sunlight at a flux of less than 1 sun (1 kilowatt per square meter). This device is capable of harvesting 2.8 liters of water per kilogram of MOF daily at relative humidity levels as low as 20% and requires no additional input of energy.

https://science.sciencemag.org/content/sci/early/2017/04/12/science.aam8743.full.pdf

Water harvesting from air with metal-organic frameworks powered by natural sunlight

If properly designed, terrestrial structures can passively cool themselves through radiative emission of heat to outer space. For the first time, we present a metal-dielectric photonic structure capable of radiative cooling in daytime outdoor conditions. The structure behaves as a broadband mirror for solar light, while simultaneously emitting strongly in the mid-IR within the atmospheric transparency window, achieving a net cooling power in excess of 100 W/m2 at ambient temperature. This cooling persists in the presence of significant convective/conductive heat exchange and nonideal atmospheric conditions.

/pdf/ultrabroadband-photonic-structures-to-achieve-high-49i4svg09r.pdf

Ultrabroadband Photonic Structures To Achieve High-Performance Daytime Radiative Cooling

The trend of continuing miniaturisation of microelectronics leads to new thermal management challenges. A key point in the heat removal process development is to improve the heat conduction across interfaces through improved thermal interface materials (TIMs). We identify the key areas for state-of-the art TIM research and investigate the current state of the field together with possible future advances.

Torbjorn M.J. Nilsson

Papers

Novel nanostructured thermal interface materials: a review

Radiative cooling during the day: simulations and experiments on pigmented polyethylene cover foils

Dew water collector for potable water in Ajaccio (Corsica Island, France)

A solar reflecting material for radiative cooling applications : ZnS pigmented polyethylene

Initial experiments on dew collection in Sweden and Tanzania